1. Field of the Invention
The present invention relates, in general, to a cooling structure for ventilation-hooded microwave ovens, and more particularly, to an improved cooling structure for effectively cooling electronic equipment generating microwaves by introducing an air current into the cooking cavity of such an oven using a cooling fan mounted to the upper portion of the microwave oven.
2. Description of the Background Art
As well known to those skilled in the art, in a conventional OTR (over the range), a microwave oven is installed over a gas oven and generates microwaves to heat food in its cooking cavity. A collateral function of the microwave oven is to exhaust the smoke of the gas oven into the atmosphere.
FIG. 1 is a schematic view showing the construction of a conventional ventilation-hooded microwave oven.
As shown in FIG. 1, such a microwave oven comprises a cavity assembly 10, including a cavity 12 for cooking, and an instrument compartment 14 mounted to the outside wall of the cooking cavity 12. Electronic equipment is embedded in the instrument compartment 14 while an air duct 20 is mounted to the top portion of the cooking cavity assembly 10.
A magnetron mount plate 13 is protrusively mounted in the instrument compartment 14. Also, both the electronic equipment for generating microwaves and an exhaust passage serving to ventilate smoke are mounted in the instrument compartment 14.
A magnetron 16 for oscillating microwaves is fixed to the mount plate 13, while a high voltage transformer 11 for supplying a high voltage to the magnetron 16 is mounted to the rear panel 10b of the instrument compartment 14.
A lower panel 18, consisting of the lower portion of the instrument compartment 14, is mounted to the front and rear panels 10a and 10b using a plurality of screws. A fan motor assembly 15, for both radiating the heat of the electronic equipment and exhausting the smoke of the cooking cavity into the atmosphere, is mounted in such a manner that the fan motor assembly 15 is spaced apart from the right-side portion of the magnetron 16 by a predetermined gap. In addition, a condenser 19 is mounted in the instrument compartment 14, while an exhaust channel 18a for forming a separated exhaust passage, is formed on the right-side portion of the lower panel 18 as shown in FIG. 1.
As mentioned above, after the electronic equipment is embedded in the instrument compartment 14, the electronic equipment is covered with an air guide plate 17 so that the exhaust passage is formed so as to connect the exhaust channel 18a to the air duct 20. That is, the right-side portion of the instrument compartment 14, corresponding to the exhaust channel 18a of the lower panel 18, is covered with the air guide plate 17, thereby forming the right-side portion of the instrument compartment 14 into the exhaust passage. Preferably, the guide plate 17 has an almost L-shaped cross-section.
An exhaust motor 22 is mounted around the rear portion of the air duct 20. The exhaust motor 22 serves to generate an air current at the exhaust passage, which communicates with a base panel 30 of the microwave oven, a part of the instrument compartment 14 and the rear portion of the air duct 20. An air intake port 24 is formed at the front side of the air duct 20 so that air is introduced into the interior of the instrument compartment 24 by the fan assembly 15 as described below.
FIGS. 2 and 3 are sectional views illustrating the mount construction of the conventional microwave oven shown in FIG. 1.
As shown FIG. 2, the fan assembly 15, serving to generate the air current, is mounted between the magnetron 16 and the high voltage transformer 11 at the intermediate height of the instrument compartment 14. In addition, as shown FIG. 3, the fan assembly 15 is mounted at a position spaced apart from the right portion of the magnetron 16 so as to generate the air current for cooling the electronic equipment.
That is, the air is introduced into the cooking cavity 12 through the air intake port 24 by the fan assembly 15. The air, passed through the fan assembly 15, is separated into two air currents. The first air current flows toward the magnetron 16 mounted to the lower panel 18, while the second air current flows toward the transformer 11, mounted to the rear panel 10b of the instrument compartment 14. Thus the electronic equipment is cooled by the introduction of the air current. Thereafter, such an air current is introduced into the cooking cavity 12 through a vent hole 12b formed on one sidewall 12a of the cavity 12. Subsequently, the air current is exhausted with the air of the cavity 12 into the atmosphere through the other side wall of the cavity 12 or a vent hole formed on the top portion of the cooking cavity 12.
However, such a conventional construction of the electronic equipment in the microwave oven has problems as described below.
The mounting positions of both the magnetron 16 and the high voltage transformer 11 are different from each other, when viewed from the position of the fan assembly 15. That is, as shown FIG. 2, the magnetron 16 is mounted to the lower panel 18, while the transformer 11 is mounted to the rear panel 10b of the instrument compartment 14. Thus, the amount of air current introduced for the magnetron 16 and the transformer 11 is insufficient because the air is separately introduced to both the magnetron 16 and the transformer 11. Also, when the air is introduced to both the magnetron 16 and the transformer 11, the direction of the air current has to be changed so as to have a predetermined angle to cool both the magnetron 16 and the transformer 1. Therefore, the cooling efficiency of the fan assembly 15 is reduced.
In addition, the fan assembly 15 is spaced apart from the air intake port 24 of the air duct 20. That is, the air passage, connecting the air intake port 24 to the fan assembly 15, is bent at an angle of 90.degree.. Thus, the blowing force of the fan assembly 15 is reduced by the distance between the fan assembly 15 and the intake port 24. Also, due to the complexity of an intake air course, the energy of the air current is reduced during the flowing of the air. Therefore, in order to intake a sufficient amount of air, the blowing force of the fan assembly 15 has to be increased. However, it is difficult to increase the blowing force of the fan assembly in the instrument compartment due to a limited area.
Also, in the fan assembly 15, a fan cover 15a has to be formed into a specifically-bent shape suitable for introducing the cooling air into both the magnetron 16 and the transformer 11. Therefore, the construction of the fan assembly 15 is complicated.